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          <th colspan="3" align="center">Db::cursor()</th>
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    <div class="sect1" lang="en" xml:lang="en">
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            <h2 class="title" style="clear: both"><a id="dbcursor"></a>Db::cursor()</h2>
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      <pre class="programlisting">#include &lt;db_cxx.h&gt;
 
int
Db::cursor(DbTxn *txnid, Dbc **cursorp, u_int32_t flags);</pre>
      <p>
        The <code class="methodname">Db::cursor()</code> method returns a created database cursor.
    </p>
      <p>
         Cursors may span threads, but only serially, that is, the application
         must serialize access to the cursor handle.
    </p>
      <p>
         The <code class="methodname">Db::cursor()</code> <span>
            
            <span>
                method either returns a non-zero error value or throws an
                exception that encapsulates a non-zero error value on
                failure, and returns 0 on success.
            </span>
        </span>
    </p>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idm2293120"></a>Parameters</h3>
            </div>
          </div>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idm2293768"></a>txnid</h4>
              </div>
            </div>
          </div>
          <p>
                          To transaction-protect cursor operations, cursors must be
                          opened and closed within the context of a transaction. The
                          <span class="bold"><strong>txnid</strong></span> parameter specifies the
                          transaction context in which the cursor may be used.
                     </p>
          <p>
                          Cursor operations are not automatically transaction-protected, even if the 
                          <a class="link" href="envset_flags.html#envset_flags_DB_AUTO_COMMIT">DB_AUTO_COMMIT</a> 
                          flag is specified to the 
                          <a class="xref" href="envset_flags.html" title="DbEnv::set_flags()">DbEnv::set_flags()</a>  or
                          <a class="xref" href="dbopen.html" title="Db::open()">Db::open()</a>  methods.  If
                          cursor operations are to be transaction-protected, the <span class="bold"><strong>txnid</strong></span> parameter must be a transaction handle
                          returned from <a class="xref" href="txnbegin.html" title="DbEnv::txn_begin()">DbEnv::txn_begin()</a>; otherwise,
                          NULL.
                      </p>
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        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp6095680"></a>cursorp</h4>
              </div>
            </div>
          </div>
          <p>
                          The <span class="bold"><strong>cursorp</strong></span> parameter references
                          memory into which a pointer to the allocated cursor is copied.
                     </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp6085968"></a>flags</h4>
              </div>
            </div>
          </div>
          <p>
                          The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
                          or by bitwise inclusively <span class="bold"><strong>OR</strong></span>'ing
                          together one or more of the following values:
                     </p>
          <div class="itemizedlist">
            <ul type="disc">
              <li>
                <p><a id="cursor_DB_BULK"></a>
                  <code class="literal">DB_CURSOR_BULK</code>
            </p>
                <p>
		 Configure a cursor to optimize for bulk operations.  Each
		 successive operation on a cursor configured with this flag
		 attempts to continue on the same database page as the previous
		 operation, falling back to a search if a different page is
		 required.  This avoids searching if there is a high degree of
		 locality between cursor operations.  This flag is currently
		 only effective with the btree access method. For other access
		 methods, this flag is ignored.
            </p>
              </li>
              <li>
                <p><a id="cursor_DB_READ_COMMITTED"></a>
                  <code class="literal">DB_READ_COMMITTED</code>
            </p>
                <p>
                 Configure a transactional cursor to have degree 2 isolation.  This
                 ensures the stability of the current data item read by this cursor but
                 permits data read by this cursor to be modified or deleted prior to
                 the commit of the transaction for this cursor.
            </p>
              </li>
              <li>
                <p><a id="cursor_DB_READ_UNCOMMITTED"></a>
                  <code class="literal">DB_READ_UNCOMMITTED</code>
            </p>
                <p>
                 Configure a transactional cursor to have degree 1 isolation.  Read
                 operations performed by the cursor may return modified but not yet
                 committed data.  Silently ignored if the 
                 <a class="link" href="dbopen.html#dbopen_DB_READ_UNCOMMITTED">DB_READ_UNCOMMITTED</a> 
                 flag was not specified when the underlying database was opened.
            </p>
              </li>
              <li>
                <p><a id="cursor_DB_WRITECURSOR"></a>
                  <code class="literal">DB_WRITECURSOR</code>
            </p>
                <p>
                 Specify that the cursor will be used to update the database.  The
                 underlying database environment must have been opened using the 
                 <a class="link" href="envopen.html#envopen_DB_INIT_CDB">DB_INIT_CDB</a>  flag.
            </p>
              </li>
              <li>
                <p><a id="cursor_DB_TXN_SNAPSHOT"></a>
                  <code class="literal">DB_TXN_SNAPSHOT</code>
            </p>
                <p>
                 Configure a transactional cursor to operate with read-only <a href="../../programmer_reference/transapp_read.html" class="olink">snapshot isolation</a>.  For
                 databases with the 
                 <a class="link" href="dbopen.html#dbopen_DB_MULTIVERSION">DB_MULTIVERSION</a> 
                 flag set, data values will be read as they are when the cursor is
                 opened, without taking read locks.  
             </p>
                <p>
                 This flag implicitly begins a transaction that is committed when the cursor is 
                 closed.
             </p>
                <p>
                 This flag is silently ignored if 
                 <a class="link" href="dbopen.html#dbopen_DB_MULTIVERSION">DB_MULTIVERSION</a> 
                 is not set on the underlying database or if a transaction is supplied in
                 the <span class="bold"><strong>txnid</strong></span> parameter.
            </p>
              </li>
            </ul>
          </div>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp6102504"></a>Errors</h3>
            </div>
          </div>
        </div>
        <p>
                         The <code class="methodname">Db::cursor()</code> <span>
            
            <span>
                method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a> 
                exception, encapsulating one of the following non-zero errors, or return one
                of the following non-zero errors:
            </span>
        </span>
                    </p>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp6094264"></a> <span>DbRepHandleDeadException or</span> DB_REP_HANDLE_DEAD</h4>
              </div>
            </div>
          </div>
          <p>
                When a client synchronizes with the master, it is possible for committed
                transactions to be rolled back. This invalidates all  the database and cursor
                handles opened in the replication environment. Once this occurs, an attempt to use
                such a handle will 
                <span>
                    throw a <a class="xref" href="dbrephandledead.html" title="DbRepHandleDeadException">DbRepHandleDeadException</a> (if
                    your application is configured to throw exceptions), or 
                </span>
                return <code class="literal">DB_REP_HANDLE_DEAD</code>.
                The application will need to discard the handle and open a new one in order to
                continue processing.
            </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp6087152"></a><span>DbDeadlockException or </span>DB_REP_LOCKOUT</h4>
              </div>
            </div>
          </div>
          <p>
                The operation was blocked by client/master synchronization.
            </p>
          <p>
                <a class="xref" href="dbdeadlock.html" title="DbDeadlockException">DbDeadlockException</a> is thrown if
                your Berkeley DB API is configured to throw exceptions.
                Otherwise, <code class="literal">DB_REP_LOCKOUT</code> is returned.
            </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp6087600"></a>EINVAL</h4>
              </div>
            </div>
          </div>
          <p>
                An invalid flag value or parameter was specified.
            </p>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp6105992"></a>Class</h3>
            </div>
          </div>
        </div>
        <p>
                <a class="link" href="db.html" title="Chapter 2.  The Db Handle">Db</a>  
            </p>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp6088712"></a>See Also</h3>
            </div>
          </div>
        </div>
        <p>
                     <a class="xref" href="dbc.html#dbclist" title="Database Cursors and Related Methods">Database Cursors and Related Methods</a> 
                </p>
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